Fair Value Measurements - Cash and Cash Equivalents (Details) - USD ($) $ in Millions	12 Months Ended
Sep. 28, 2024	Sep. 30, 2023
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cost	$ 2,160.2	$ 2,722.5
Cost	173.4	0.0
Total	2,428.4
Unrealized Gains	1.6
Unrealized Losses	0.0
Fair Value	992.9	$ 0.0
Total	2,430.0
Investments	269.8
Cash
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cost	1,437.1
Fair Value	1,437.1
Money Market Funds
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cost	341.7
Cost	341.7
Unrealized Gains	0.0
Unrealized Losses	0.0
Fair Value	341.7
Fair Value	341.7
Investments	0.0
US Treasury Securities
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cost	356.5
Cost	624.7
Investments, Unrealized Gain	1.6
Investments, Unrealized Loss	0.0
Fair Value	626.3
Investments	269.8
Commercial Paper
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cost	24.9
Unrealized Gains	0.0
Unrealized Losses	0.0
Fair Value	24.9
Investments	$ 0.0

Cash, Cash Equivalents, and Short-Term Investments, Fair Value

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Investments, Unrealized Gain

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Amount of currency on hand as well as demand deposits with banks or financial institutions. Includes other kinds of accounts that have the general characteristics of demand deposits. Also includes short-term, highly liquid investments that are both readily convertible to known amounts of cash and so near their maturity that they present insignificant risk of changes in value because of changes in interest rates. Excludes cash and cash equivalents within disposal group and discontinued operation.

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Fair value portion of currency on hand as well as demand deposits with banks or financial institutions. Includes other kinds of accounts that have the general characteristics of demand deposits. Also includes short-term, highly liquid investments that are both readily convertible to known amounts of cash and so near their maturity that they present insignificant risk of changes in value because of changes in interest rates.

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Cash includes currency on hand as well as demand deposits with banks or financial institutions. It also includes other kinds of accounts that have the general characteristics of demand deposits in that the customer may deposit additional funds at any time and effectively may withdraw funds at any time without prior notice or penalty. Cash equivalents, excluding items classified as marketable securities, include short-term, highly liquid Investments that are both readily convertible to known amounts of cash, and so near their maturity that they present minimal risk of changes in value because of changes in interest rates. Generally, only investments with original maturities of three months or less qualify under that definition. Original maturity means original maturity to the entity holding the investment. For example, both a three-month US Treasury bill and a three-year Treasury note purchased three months from maturity qualify as cash equivalents. However, a Treasury note purchased three years ago does not become a cash equivalent when its remaining maturity is three months. Short-term investments, exclusive of cash equivalents, generally consist of marketable securities intended to be sold within one year (or the normal operating cycle if longer) and may include trading securities, available-for-sale securities, or held-to-maturity securities (if maturing within one year), as applicable.

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Amortized cost excluding accrued interest, after allowance for credit loss, of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

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Amount excluding accrued interest, of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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Sum of the carrying amounts as of the balance sheet date of all investments.

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Amount of investments including trading securities, available-for-sale securities, held-to-maturity securities, and short-term investments classified as other and current.

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